Goals of our study were: 1. to assess quality of our analytical work and application of concepts of good laboratory practice using different EQA surveys, 2. to evaluate performance and efficiency of systems for internal quality control using EQA program that is independent on local subjective and objective influences and 3. to observe how single EQA programs differ and how they contribute the ability of laboratories to manage their overall quality. Using one-way ANOVA, we compared our 1999 results in the local EQA survey AKS (SEKK s r.o., Czech Republic) to our results in CN3 Comprehensive Chemistry Survey (College of American Pathologists, USA) for analyses provided in CN3 with the definitive method correlated target values, the design of which assures accuracy of the field methods on patient specimens. In 4 out of 9 methods, the material AKS predicted target values that were significantly different from that of CN3; calcium sodium, uric acid and cholesterol. The CN3 survey provided link of our results of internal quality control and national EQA to the largest proficiency testing available worldwide in clinical chemistry. Out data suggest that a possibility exists to improve the design of target values for materials used for small national EQA surveys as well as the program administration so that local characteristics of field method on patient specimens could be better monitored.

        Key words: routine laboratory results, external quality control, sodium, kalium, calcium, magnesium, creatinin, uric acid, cholesterol.